When Namjoon beats Y/N

Kim Namjoon is a 25 year old doctor. He is very smart and have 148 IQ.He is very kind -hearted and sweet brother. He always helps and respects everyone. Their parents mostly live in abroad due to their business works.
Kim Y/N is a 15 year old teenager. She is also kind hearted and sweet sister. She always helps and respects everyone. She is very good in studies and she is a topper. She have a best friend Jungkook.